The Mass Balance

The general balance equation which is the basis for all mass and heat equations is as follows :
MASS IN - RAW MATERIALS CONSUMED + GENERATION = MASS OUT (product & waste)

Using the above process, there are four possible explanations if :
X in != X out

1. There is a loss of X from the process units or pipes
2. X is being consumed as a reactant in the process unit or alternatively being generated as a product within the unit.